And a further seven per cent have faced untrue claims from a student's parent or family member.

The study found that many teachers live in such fear of being falsely accused that they're considering leaving the profession altogether.

One experienced teacher told the ATL that she felt vulnerable as pupils 'twist things that are said'.Another said her husband was left a 'broken man' who died of a heart attack at the age of 50 after false allegations were made about him.

A Kent primary school teacher said: "Poor parental discipline is leading to children always wanting their way.

"Unable to discipline children without a comeback has meant this sort of incident will escalate and very good teachers will be driven out when they are most needed."

The ATL's survey found that 22 per cent of teachers said they had faced a false allegation made by a pupil and that 14.3 per cent had faced claims by a pupil's parent or other family member.

More than a third of those polled said that someone in their current school or college had had an untrue allegation made against them by a student, with a further 22.6 per cent saying a colleague had faced claims from a student's relative.

The ATL said false allegations are blighting careers and putting added stress on to education workers.David Guiterman, ATL's branch secretary in Cornwall, said: "Even if the allegation is shown to be false it leaves a lasting scar. In a local case, a member decided to resign, even though the allegation was shown to be false. He did not want to carry on lecturing."

ATL general secretary Dr Mary Bousted added: "Schools and colleges need to recognise that young people sometimes make up allegations - they may be angry, under stress, suffering problems at home or have a host of other reasons – and take this into account when investigating them."

The survey questioned 685 members working in schools and colleges in England, Wales and Northern Ireland between 19 February and 10 March this year.

A Department for Education spokesman said: "We understand the variety of pressures teachers face, which is why through our plan for education we have taken a number of measures to support them.

"We recognise the extreme damage which can be caused to teachers who have false allegations made against them, which is why we have made clear to schools and colleges that staff should be supported throughout, and are able to return to focusing their energies on teaching as swiftly as possible."